View source for Biology:Bovine malignant catarrhal fever

{{Short description|Species of virus}}
{{virusbox
| parent = Macavirus
| species           = Alcelaphine gammaherpesvirus 1 (AlHV-1), Ovine gammaherpesvirus 2 (OHV-2)
}}
[[File:Malignant catarrhal fever eye large ring.jpg|thumb|289x289px|Eye Ring]]
'''Bovine malignant catarrhal fever''' ('''BMCF''') is a fatal lymphoproliferative disease<ref name=OToole2014>{{cite journal |doi=10.1177/0300985813520435 |pmid=24503439 |title=The Pathology of Malignant Catarrhal Fever, with an Emphasis on Ovine Herpesvirus 2 |journal=Veterinary Pathology |publisher=ACVP ECVP JCVP ([[Company:SAGE Publishing|Sage]]) |volume=51 |issue=2 |pages=437–452 |year=2014 |last1=o'Toole |first1=D. |last2=Li |first2=H.|doi-access=free }}</ref> caused by a group of ruminant gamma herpes viruses including '''''Alcelaphine gammaherpesvirus 1''''' ('''AlHV-1''')<ref name="Plowright W_1960">{{cite journal |doi=10.1038/1881167a0 |pmid=13736396 |title=Blue Wildebeest and the Ætiological Agent of Bovine Malignant Catarrhal Fever |journal=Nature |volume=188 |issue=4757 |pages=1167–1169 |year=1960 |last1=Plowright |first1=W. |last2=Ferris |first2=R. D. |last3=Scott |first3=G. R. |bibcode=1960Natur.188.1167P|s2cid=37101022 }}</ref> and '''''Ovine gammaherpesvirus 2''''' ('''OvHV-2''')<ref name=OToole2014 /><ref>{{Cite journal |doi=10.1177/104063870001200602 |pmid=11108448 |title=Epizootic Malignant Catarrhal Fever in Three Bison Herds: Differences from Cattle and Association with Ovine Herpesvirus-2 |journal=Journal of Veterinary Diagnostic Investigation |volume=12 |issue=6 |pages=497–502 |year=2000 |last1=Schultheiss |first1=Patricia C. |last2=Collins |first2=James K. |last3=Spraker |first3=Terry R. |last4=Demartini |first4=James C.|doi-access=free }}</ref> These viruses cause unapparent infection in their reservoir hosts (sheep with OvHV-2 and wildebeest with AlHV-1), but are usually fatal in [[Biology:Cattle|cattle]] and other [[Biology:Ungulate|ungulate]]s such as [[Biology:Deer|deer]], [[Biology:Antelope|antelope]], and buffalo.<ref name="Plowright W_1960"/> In Southern Africa the disease is known as ''snotsiekte'', from the [[Social:Afrikaans|Afrikaans]].<ref name="WilliamsBarker2008">{{cite book |author1=Elizabeth S. Williams |author2=Ian K. Barker |title=Infectious Diseases of Wild Mammals |url=https://books.google.com/books?id=HJDsAU-NWiYC&pg=PA157 |date=28 February 2008 |publisher=John Wiley & Sons |isbn=978-0-470-34481-1 |pages=157–}}</ref><ref name="TalbotTalbot1963">{{cite book |author1=Lee Merriam Talbot |author2=Martha H. Talbot |title=The Wildebeest in Western Masailand, East Africa |url=https://books.google.com/books?id=gEMrAAAAYAAJ&pg=PA52 |year=1963 |publisher=National Academies |pages=52– |id=NAP:13180}}</ref>

BMCF is an important disease where reservoir and susceptible animals mix. There is a particular problem with Bali cattle in Indonesia,<ref name="Wiyono A_1994">{{Cite journal |pmid=7839584 |year=1994 |last1=Wiyono |first1=A. |title=PCR detection of ovine herpesvirus-2 DNA in Indonesian ruminants--normal sheep and clinical cases of malignant catarrhal fever |journal=Veterinary Microbiology |volume=42 |issue=1 |pages=45–52 |last2=Baxter |first2=S. I. |last3=Saepulloh |first3=M. |last4=Damayanti |first4=R. |last5=Daniels |first5=P. |last6=Reid |first6=H. W.|doi=10.1016/0378-1135(94)90076-0 }}</ref> bison in the US<ref name="Berezowski JA_2005">{{Cite journal |doi=10.1177/104063870501700110 |pmid=15690951 |title=An Outbreak of Sheep-Associated Malignant Catarrhal Fever in Bison (Bison Bison) after Exposure to Sheep at a Public Auction Sale |journal=Journal of Veterinary Diagnostic Investigation |volume=17 |issue=1 |pages=55–58 |year=2005 |last1=Berezowski |first1=John Andrew |last2=Appleyard |first2=Greg D. |last3=Crawford |first3=Timothy B. |last4=Haigh |first4=Jerry |last5=Li |first5=Hong |last6=Middleton |first6=Dorothy M. |last7=O'Connor |first7=Brendan P. |last8=West |first8=Keith |last9=Woodbury |first9=Murray|s2cid=43134613 |doi-access= }}</ref> and in pastoralist herds in Eastern and Southern Africa.<ref name="Cleaveland S_2001">{{cite web|author1=Cleaveland S |author2=Kusiluka L |author3=Ole Kuwai J |author4=Bell C |author5=Kazwala R. |date=2001 |title=Assessing the impact of Malignant Catarrhal Fever in Ngorongoro District, Tanzania.|pages=57–72|publisher=Animal Health Programme, Department for International Development|url=https://www.researchgate.net/publication/237121941|format=PDF|access-date=9 September 2020}}</ref><ref name="Bedelian C_2007">{{Cite journal |doi=10.1016/j.prevetmed.2006.10.012 |pmid=17123651 |title=Maasai perception of the impact and incidence of malignant catarrhal fever (MCF) in southern Kenya |journal=Preventive Veterinary Medicine |volume=78 |issue=3–4 |pages=296–316 |year=2007 |last1=Bedelian |first1=Claire |last2=Nkedianye |first2=David |last3=Herrero |first3=Mario}}</ref>

Disease outbreaks in cattle are usually sporadic although infection of up to 40% of a herd has been reported. The reasons for this are unknown. Some species appear to be particularly susceptible, for example Père David's deer,<ref name="Reid H_1987">{{Cite journal |doi=10.1080/00480169.1988.35466 |pmid=16031426 |title=An outbreak of malignant catarrhal fever in Père David's deer (Elaphurus davidianus) |journal=New Zealand Veterinary Journal |volume=36 |issue=1 |pages=19–21 |year=1988 |last1=Orr |first1=M.B. |last2=MacKintosh |first2=C.G.}}</ref> Bali cattle<ref name="Wiyono A_1994"/> and bison,<ref name="Berezowski JA_2005"/> with many deer dying within 48 hours of the appearance of the first symptoms and bison within three days.<ref name=OToole2014 /><ref name=O2002>{{Cite journal |doi=10.1177/104063870201400301 |pmid=12033673 |title=Malignant Catarrhal Fever in a Bison (Bison Bison) Feedlot, 1993–2000 |journal=Journal of Veterinary Diagnostic Investigation |volume=14 |issue=3 |pages=183–193 |year=2002 |last1=O'Toole |first1=D. |last2=Li |first2=H. |last3=Sourk |first3=C. |last4=Montgomery |first4=D. L. |last5=Crawford |first5=T. B.|doi-access=free }}</ref> In contrast, post infection cattle will usually survive a week or more.<ref name="Holliman A_2007">{{Cite journal |doi=10.1136/vr.161.14.494-e |pmid=17921444 |title=Malignant catarrhal fever in cattle in the UK |journal=Veterinary Record |volume=161 |issue=14 |pages=494–495 |year=2007 |last1=Holliman |first1=A. |last2=Daniel |first2=R. |last3=Twomey |first3=D. F. |last4=Barnett |first4=J. |last5=Scholes |first5=S. |last6=Willoughby |first6=K. |last7=Russell |first7=G.|s2cid=26446432 }}</ref>

==Epidemiology==
The term ''bovine malignant catarrhal fever'' has been applied to three different patterns of disease:
*In [[Earth:Africa|Africa]], [[Biology:Wildebeest|wildebeest]]s carry a lifelong infection of AlHV-1 but are not affected by the disease.<ref name="Plowright W_1960"/> The virus is passed from mother to offspring and shed mostly in the nasal secretions of wildebeest calves under one year old.<ref name="Mushi EZ_1981">{{cite journal |last1=Mushi |first1=E. Z. |last2=Rurangirwa |first2=F. R. |journal=Bulletin of Animal Health and Production in Africa |year=1981 |volume=29 |issue=1 |pages=111–2 |title=Malignant catarrhal fever virus shedding by infected cattle |pmid=7296019 }}</ref><ref name="Baxter S_1997">{{cite journal |last1=Baxter |first1=S. I. |last2=Wiyono |first2=A. |last3=Pow |first3=I. |last4=Reid |first4=H. W. |title=Identification of Ovine Herpes Virus-2 infection in sheep |journal=Archives of Virology |volume=142 |issue=4 |year=1997 |pages=823–831 |doi=10.1007/s007050050121 |pmid=9170507 |s2cid=30143095 }}</ref> Wildebeest associated MCF is transmitted from wildebeest to cattle normally following the wildebeest calving period. Cattle of all ages are susceptible to the disease, with a higher infection rate in adults, particularly in peripartuent females.<ref name="Barnard B_1994">{{cite book |last1=Barnard |first1=B. J. |last2=Van der Lugt |first2=J. J. |last3=Mushi |first3=E. Z. |chapter=Malignant Catarrhal Fever |editor-first=J. A. W. |editor-last=Coetzer |editor2-first=G. R. |editor2-last=Thompson |editor3-first=R. C. |editor3-last=Tustin |title=Infectious Diseases of Livestock |publisher=Oxford University Press |location=New York |year=1994 |isbn=978-0-19-570506-5 }}</ref> Cattle are infected by contact with the secretions, but do not spread the disease to other cattle. Because no commercial treatment or vaccine is available for this disease, livestock management is the only method of control. This involves keeping cattle away from wildebeest during the critical calving period. This results in Massai pastoralists in Tanzania and Kenya being excluded from prime pasture grazing land during the wet season leading to a loss in productivity.<ref name="Homewood KH_1987">{{cite journal |last1=Homewood |first1=K. H. |last2=Rodgers |first2=W. A. |last3=Arhem |first3=K. |title=Ecology of pastoralism in Ngorongoro Conservation Area, Tanzania |journal=The Journal of Agricultural Science |volume=108 |year=1987 |pages=47–72 |doi=10.1017/S0021859600064133 |s2cid=86547027 }}</ref> In Eastern and Southern Africa MCF is classed as one of the five most important problems affecting pastoralists along with East coast fever, [[Biology:Contagious bovine pleuropneumonia|contagious bovine pleuropneumonia]], foot and mouth disease and [[Medicine:Anthrax|anthrax]].<ref name="Boone RB_2001">{{cite report |last1=Boone |first1=R. B. |last2=Coughenour |first2=M. B. |year=2001 |title=A system for integrated management and assessment of east African pastoral lands. Balancing food security, wildlife conservation, and ecosystem integrity |work=Final report to the Global Livestock Collaborative Research Support Program}}</ref> [[Biology:Hartebeest|Hartebeest]]s and [[Biology:Topi|topi]] also may carry the disease.<ref name=Fenner_1993>{{cite book |last1=Fenner |first1=Frank J. |last2=Gibbs |first2=E. |last3=Paul |first3=J. |last4=Murphy |first4=Frederick A. |last5=Rott |first5=Rudolph |last6=Studdert |first6=Michael J. |last7=White |first7=David O. |title=Veterinary Virology |edition=2nd |publisher=Academic Press |year=1993 |isbn=978-0-12-253056-2 }}</ref> However, hartebeests and other antelopes are infected by a variant, [[Biology:Alcelaphine herpesvirus 2|Alcelaphine herpesvirus 2]].
*Throughout the rest of the world, cattle and deer contract BMCF by close contact with [[Biology:Sheep|sheep]] or goats during lambing. The natural host reservoir for Ovine herpesvirus 2 is the subfamily Caprinae (sheep and goats) whilst MCF affected animals are from the families Bovidae, Cervidae and suidae.<ref name=O2007>{{Cite journal |doi=10.1354/vp.44-5-655 |pmid=17846237 |title=Intra-nasal Inoculation of American Bison (Bison bison) with Ovine Herpesvirus-2 (OvHV-2) Reliably Reproduces Malignant Catarrhal Fever |journal=Veterinary Pathology |volume=44 |issue=5 |pages=655–662 |year=2007 |last1=O'Toole |first1=D. |last2=Taus |first2=N. S. |last3=Montgomery |first3=D. L. |last4=Oaks |first4=J. L. |last5=Crawford |first5=T. B. |last6=Li |first6=H.|s2cid=7232660 |doi-access= }}</ref><ref name="Taus NS_2007">{{Cite journal |doi=10.1099/vir.0.82285-0 |pmid=17170434 |title=Comparison of ovine herpesvirus 2 genomes isolated from domestic sheep (Ovis aries) and a clinically affected cow (Bos bovis) |journal=Journal of General Virology |volume=88 |issue=Pt 1 |pages=40–45 |year=2007 |last1=Taus |first1=N. S. |last2=Herndon |first2=D. R. |last3=Traul |first3=D. L. |last4=Stewart |first4=J. P. |last5=Ackermann |first5=M. |last6=Li |first6=H. |last7=Knowles |first7=D. P. |last8=Lewis |first8=G. S. |last9=Brayton |first9=K. A.|doi-access=free }}</ref> Susceptibility to OHV-2 varies by species, with domestic cattle and [[Biology:Zebu|zebu]]s somewhat resistant, water buffalo and most deer somewhat susceptible, and [[Biology:Bison|bison]], [[Biology:Bali cattle|Bali cattle]], and [[Biology:Père David's deer|Père David's deer]] very susceptible.<ref name=CFSPH_2005>{{cite web |year=2005 |title=Malignant Catarrhal fever |work=The Center for Food Security and Public Health at Iowa State University |url=http://www.cfsph.iastate.edu/Factsheets/pdfs/malignant_catarrhal_fever.pdf |access-date=2006-05-13}}</ref> OHV-2 viral DNA has been detected in the alimentary, respiratory and urino-genital tracts of sheep<ref name="Hüssy D_2001">{{Cite journal |doi=10.1128/CDLI.8.1.123-128.2001 |pmid=11139205 |pmc=96020 |title=Quantitative Fluorogenic PCR Assay for Measuring Ovine Herpesvirus 2 Replication in Sheep |journal=Clinical and Vaccine Immunology |volume=8 |issue=1 |pages=123–128 |year=2001 |last1=Hussy |first1=D. |last2=Stauber |first2=N. |last3=Leutenegger |first3=C. M. |last4=Rieder |first4=S. |last5=Ackermann |first5=M.}}</ref> all of which could be possible transmission routes. [[Biology:Antibody|Antibody]] from sheep and from cattle with BMCF is cross reactive with AlHV-1.<ref name=Fenner_1993/>
*AHV-1/OHV-2 can also cause problems in zoological collections, where inapparently infected hosts (wildebeest and sheep) and susceptible hosts are often kept in close proximity.<ref name="Cooley AJ_2008">{{Cite journal |doi=10.1638/2007-0181.1 |pmid=18817000 |title=Development of a Management Program for a Mixed Species Wildlife Park Following an Occurrence of Malignant Catarrhal Fever |journal=Journal of Zoo and Wildlife Medicine |volume=39 |issue=3 |pages=380–385 |year=2008 |last1=Cooley |first1=A. Jim |last2=Taus |first2=Naomi S. |last3=Li |first3=Hong|s2cid=24137474 }}</ref>
*Feedlot bison in North America not in contact with sheep have also been diagnosed with a form of BMCF. OHV-2 has been recently documented to infect herds of up to 5&nbsp;km away from the nearest lambs, with the levels of infected animals proportional to the distance away from the closest herds of sheep.<ref name=LiH_2008>{{Cite journal |pmid=18309750 |pmc=2216446 |year=2008 |last1=Li |first1=H. |title=Long distance spread of malignant catarrhal fever virus from feedlot lambs to ranch bison |journal=The Canadian Veterinary Journal |volume=49 |issue=2 |pages=183–5 |last2=Karney |first2=G. |last3=O'Toole |first3=D. |last4=Crawford |first4=T. B.}}</ref>
The [[Medicine:Incubation period|incubation period]] of BMCF is not known, however intranasal challenge with AHV-1 induced MCF in one hundred percent of challenged cattle between 2.5 and 6 weeks.<ref name="Haig DM_2008">{{Cite journal |doi=10.1016/j.vaccine.2008.06.056 |pmid=18601965 |title=An immunisation strategy for the protection of cattle against alcelaphine herpesvirus-1-induced malignant catarrhal fever |journal=Vaccine |volume=26 |issue=35 |pages=4461–4468 |year=2008 |last1=Haig |first1=David M. |last2=Grant |first2=Dawn |last3=Deane |first3=David |last4=Campbell |first4=Iris |last5=Thomson |first5=Jackie |last6=Jepson |first6=Catherine |last7=Buxton |first7=David |last8=Russell |first8=George C.}}</ref>
Shedding of the virus is greater from 6–9 month old lambs than from adults.<ref name=OToole2014 /> After experimental infection of sheep, there is limited viral replication in nasal cavity in the first 24 hours after infection, followed by later viral replication in other tissues.<ref name=OToole2014 />

==Clinical signs==
The most common form of the disease is the head and eye form. Typical symptoms of this form include fever, depression, discharge from the eyes and nose, lesions of the buccal cavity and muzzle, swelling of the [[Biology:Lymphatic system|lymph nodes]], [[Physics:Opacity (optics)|opacity]] of the [[Medicine:Cornea|cornea]]s leading to blindness, inappetence and diarrhea. Some animals have neurologic signs, such as [[Medicine:Ataxia|ataxia]], nystagmus, and [[Biology:Head pressing|head pressing]]. Animals that become infected with the virus can become extremely sensitive to touch, especially around the head. It is also possible that become aggressive and charge at approaching animals and people. If the virus continues untreated, seizures could develop. Affected animal usually die five to ten days of the first signs of clinical signs. Once the cow shows clinical signs there is no chance of recovering.<ref>{{Cite web|url=https://www.nadis.org.uk/disease-a-z/cattle/malignant-catarrhal-fever-mcf/|title=NADIS Animal Health Skills - Malignant Catarrhal Fever (MCF)|website=www.nadis.org.uk|access-date=2019-04-02}}</ref>

Peracute, alimentary and cutaneous clinical disease patterns have also been described.<ref name="OIE_2004">{{cite book |author=OIE |title=OIE Manual of Diagnostic Tests and Vaccines for terrestrial Animal |edition=5th |location=France |pages=570–579}}</ref> Death usually occurs within ten days.<ref name="Carter">{{cite web |author1=Carter, G.R. |author2=Flores, E.F. |author3=Wise, D.J. |year=2006 |title=Herpesviridae |work=A Concise Review of Veterinary Virology | url=http://www.ivis.org/advances/Carter/Part2Chap11/chapter.asp?LA=1 |access-date=2006-06-10}}</ref> The mortality rate in symptomatic animals is 90 to 100%<ref name="CFSPH_2005" /> Treatment is supportive only.

== Factors ==
There are many factors that can increase the chances of infection or affect the severity of an outbreak. The number of animals in the herd, population density and species of the susceptible hosts are huge factors. Other factors include closeness of contact and amount of virus available for transmission.<ref name=":0">{{Cite web|url=https://www.merckvetmanual.com/generalized-conditions/malignant-catarrhal-fever/overview-of-malignant-catarrhal-fever|title=Overview of Malignant Catarrhal Fever - Generalized Conditions|website=Merck Veterinary Manual|language=en-US|access-date=2019-04-02}}</ref>

==Diagnosis==
Diagnosis of BMCF depends on a combination of history and symptoms, histopathology<ref name="OIE_2004"/> and detection in the blood or tissues of viral antibodies by ELISA<ref name="Fraser SJ_2006">{{Cite journal |doi = 10.1016/j.vetmic.2006.03.002|pmid = 16621342|title = Development of an enzyme-linked immunosorbent assay for the detection of antibodies against malignant catarrhal fever viruses in cattle serum|journal = Veterinary Microbiology|volume = 116|issue = 1–3|pages = 21–28|year = 2006|last1 = Fraser|first1 = S.J.|last2 = Nettleton|first2 = P.F.|last3 = Dutia|first3 = B.M|last4 = Haig|first4 = D.M.|last5 = Russell|first5 = G.C.}}</ref><ref name="Li H_2001">{{Cite journal |doi = 10.1177/104063870101300417|pmid = 11478614|title = A Simpler, More Sensitive Competitive Inhibition Enzyme-Linked Immunosorbent Assay for Detection of Antibody to Malignant Catarrhal Fever Viruses|journal = Journal of Veterinary Diagnostic Investigation|volume = 13|issue = 4|pages = 361–364|year = 2001|last1 = Li|first1 = Hong|last2 = McGuire|first2 = Travis C.|last3 = Müller-Doblies|first3 = Uwe U.|last4 = Crawford|first4 = Timothy B.|doi-access = free}}</ref> or of viral DNA by PCR.<ref name="Hüssy D_2001"/><ref name="Cunha CW_2009">{{Cite journal |doi = 10.1128/JCM.00997-09|pmid = 19494077|title = Development of a Multiplex Real-Time PCR for Detection and Differentiation of Malignant Catarrhal Fever Viruses in Clinical Samples|journal = Journal of Clinical Microbiology|volume = 47|issue = 8|pages = 2586–2589|year = 2009|last1 = Cunha|first1 = C. W.|last2 = Otto|first2 = L.|last3 = Taus|first3 = N. S.|last4 = Knowles|first4 = D. P.|last5 = Li|first5 = H.|pmc = 2725674}}</ref><ref name="Traul DL_2007">{{Cite journal |doi = 10.1177/104063870701900412|pmid = 17609352|title = Validation of Nonnested and Real-Time PCR for Diagnosis of Sheep-Associated Malignant Catarrhal Fever in Clinical Samples|journal = Journal of Veterinary Diagnostic Investigation|volume = 19|issue = 4|pages = 405–408|year = 2007|last1 = Traul|first1 = Donald L.|last2 = Taus|first2 = Naomi S.|last3 = Oaks|first3 = J. Lindsay|last4 = Toole|first4 = Donal O'|last5 = Rurangirwa|first5 = Fred R.|last6 = Baszler|first6 = Timothy V.|last7 = Li|first7 = Hong|doi-access = free}}</ref> The characteristic histologic lesions of MCF are lymphocytic arteritis with necrosis of the blood vessel wall and the presence of large T lymphocytes mixed with other cells.<ref name=OToole2014 /> The similarity of MCF clinical signs to other enteric diseases, for example blue tongue, mucosal disease and foot and mouth make laboratory diagnosis of MCF important.<ref name="Bexiga R_2007">{{Cite journal |pmid = 18156595|year = 2007|last1 = Bexiga|first1 = R.|title = Clinical differentiation of malignant catarrhal fever, mucosal disease and bluetongue|journal = The Veterinary Record|volume = 161|issue = 25|pages = 858–9|last2 = Guyot|first2 = H.|last3 = Saegerman|first3 = C.|last4 = Mauroy|first4 = A.|last5 = Rollin|first5 = F.|last6 = Thiry|first6 = E.|last7 = Philbey|first7 = A. W.|last8 = Logue|first8 = D. N.|last9 = Mellor|first9 = D. J.|last10 = Barrett|first10 = D. C.|last11 = Ellis|first11 = K.}}</ref> The world organisation for animal health<ref name="OIE_2004"/> recognises histopathology as the definitive diagnostic test, but laboratories have adopted other approaches with recent developments in molecular virology. No vaccine has as yet been developed.

AlHV-1 and [[Biology:Ovine gammaherpesvirus 2|OvHV-2]] are almost indistinguishable without molecular sequencing. However Anderson et al 2008 do find some usable differences, mostly necrosis or lack of necrosis, and lymphoid accumulation.<ref name="Li-et-al-2014" />

==Life cycle==
Infection of [[Biology:T cell|T cell]]s is typical of MCF group viruses. This was discovered by Nelson et al 2010 by experimental infection of ''Bison bison'' with ovine strains.<ref name="Li-et-al-2014" /><ref name="OToole2014" /> They additionally found B lymphocytes to be present but irrelevant in MCF lesions.<ref name="OToole2014" />

==Ovine==
Ovine strains have been investigated by Meier-Trummer et al 2009 ([[Biology:Ovine gammaherpesvirus 2|OvHV-2]] experimentally in rabbit) and Nelson et al 2013 (SA-MCF experimentally in ''Bison bison''), both finding these to be lytic viruses.<ref name="Li-et-al-2014">{{cite journal | last1=Li | first1=Hong | last2=Cunha | first2=Cristina W. | last3=Taus | first3=Naomi S. | last4=Knowles | first4=Donald P. | title=Malignant Catarrhal Fever: Inching Toward Understanding | journal=Annual Review of Animal Biosciences | publisher=Annual Reviews | volume=2 | issue=1 | date=2014-02-01 | issn=2165-8102 | doi=10.1146/annurev-animal-022513-114156 | pages=209–233| pmid=25384141 }}</ref>

==Bovine==
===''Bison''===
''Bison bison'' are found by Nelson et al 2010 to suffer widespread mucosal [[Biology:Necrosis|necrosis]] but rarely occlusive [[Medicine:Thrombosis|thrombosis]], and they judge thrombosis to be hardly able to explain the incidences{{verify spelling|date=September 2022|reason=''incidence'' is normally used only in the singular form, perhaps ''incidence'', ''incidents'',  or ''instances'' was intended}} of necrosis.<ref name="OToole2014" />

Nelson also find CD8{{sup|+}} and CD3{{sup|+}} to be the most common immune cell types in lesions.<ref name="OToole2014" />

===''Bos''===
CD8{{sup|+}} and CD4{{sup|+}} are the most common immune cell types in lesions found by Nelson et al 2010.<ref name="OToole2014" />

== Prognosis ==
Bovine malignant catarrhal fever usually is fatal in susceptible species like cattle and bison, and any animal that survives will remain infectious for the rest of its life even if it shows no subsequent signs of the disease. Such survivors may relapse and suffer attacks in later life, but what is of more practical importance is that animals with latent infections may be unrecognised carriers that cause unexplained cases. This possibility must be borne in mind when seeking the source of mysterious outbreaks.<ref name=":0" />

==Vaccine==
Unfortunately a vaccine for malignant catarrhal fever (MCF) has not yet been developed.<ref name=OToole2014 /> Developing a vaccine has been difficult because the virus will not grow in cell culture and until recently it was not known why. Researchers at the [[Organization:Agricultural Research Service|Agricultural Research Service]] (ARS) found that the virus undergoes changes within the animal's body, a process known as "cell tropism switching". In cell tropism switching, the virus targets different cells at different points in its life cycle. This phenomenon explains why it has been impossible to grow the virus on any one particular cell culture.
 
Because the virus is transmitted from sheep to bison and cattle, researchers are first focusing on the viral life cycle in sheep. The viral life cycle is outlined in three stages: entry, maintenance, and shedding. Entry occurs through the sheep's nasal cavity and enters into the lungs where it replicates. The virus undergoes a tropic change and infects lymphocytes, also known as white blood cells, which play a role in the sheep's immune system. In the maintenance stage the virus remains on the sheep's lymphocytes and circulates the body. Finally, during the shedding stage, the virus undergoes another change and shifts its target cells from lymphocytes to nasal cavity cells, where it is then shed through nasal secretions.<ref name=ARS>{{cite web | url=http://www.ars.usda.gov/is/AR/archive/apr10/animal0410.htm | title=Figuring Out Puzzling Animal Diseases | access-date=July 9, 2017 | archive-url=https://web.archive.org/web/20100405072452/http://www.ars.usda.gov/is/AR/archive/apr10/animal0410.htm | date=2010-04-02 | archive-date=2010-04-05 |publisher=USDA Agricultural Research Service }}</ref> This discovery undoubtedly puts scientists on the right track for developing a vaccine – starting with the correct cell culture for each stage of the virus lifecycle – but ARS researchers are also looking into alternative methods to develop a vaccine. Researchers are experimenting with the MCF virus that infects [[Biology:Topi|topi]] (an African antelope) because it will grow in cell culture and does not infect cattle. Researchers hope that inserting genes from the sheep MCF virus into the topi MCF virus will ultimately be an effective MCF vaccine for cattle and bison.<ref name=ARS/> While there is much ground left to cover, scientists are getting closer and closer to developing a vaccine.

==References==
{{Reflist|30em}}

==External links==
*[https://www.oie.int/wahis_2/public/wahid.php/Diseaseinformation/Immsummary Current status of Bovine malignant catarrhal fever worldwide] at OIE. WAHID Interface - OIE World Animal Health Information Database
*[https://www.oie.int/en/animal-health-in-the-world/technical-disease-cards/ Disease card]

{{Herpesvirales}}
{{Taxonbar|from=Q552330}}

{{DEFAULTSORT:Bovine Malignant Catarrhal Fever}}
[[Category:Gammaherpesvirinae]]

{{Sourceattribution|Bovine malignant catarrhal fever}}